| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment device and an exhaust gas treatment method improving ammonia formation rate from urea and improving NOx conversion efficiency at the time of low exhaust gas temperature at engine start. <P>SOLUTION: The exhaust gas treatment device includes a front stage oxidation catalyst increasing oxidation activity of NO in exhaust gas, SCR catalyst reducing NOx in exhaust gas by ammonia, and a rear stage oxidation catalyst removing ammonia in this order from an upstream side in an exhaust gas passage of an engine, and adds urea water to a part between the front stage oxidation catalyst and the SCR catalyst. The device is provided with a control means adding urea water of a prescribed quantity when the temperature of exhaust gas is less than hydrolysis temperature of urea but not less than evaporation temperature of urea water during engine start, and executing control for raising the exhaust gas temperature up to the hydrolysis temperature of urea. <P>COPYRIGHT: (C)2010,JPO&INPIT |
